The present invention relates to copper wire for intrauterine contraceptive devices, the copper wire having a core wire owing corrosion-resistivity against uterine fluids, and to a method for manufacturing such copper wire.
It has been observed that, due to the dissolution in the uterus, copper wire often corrodes locally, and consequently the wire fragmentates and disintegrates before all of the copper has dissolved. This decreases the effective using time of intrauterine devices. In the publication "Fertility and Sterility", 30 (1) (1978) 59-65, it is pointed out that in the copper T-200 (manufactured by Hallmark Plastics Inc, U.S.A.) devices investigated, fragmentation was detected in one case after only 8 months of use. Previous studies [Population Council's Report (NDA), Wire Fragmentation, 1973] have shown severe corrosion and fragmentation in the copper wire of a intrauterine device after only 5 months of use.
In all present available intrauterine copper devices the problem is the reduced using time due to the corrosion and fragmentation of the copper wires used in them. It has been suggested that copper can be deposited electrolytically on a stainless wire, in order to avoid described disadvantage. In this case, the actual wire consists of stainless steel. Stainless, acid-resistant steel or other such kind of alloys are, however, quite rigid and thus not suitable for use in intrauterine devices. Furthermore, electrolytically coated copper may flake when corrosion reaches the steel. Furthermore, it can be assumed that, owing to electrochemical difference in voltage between the steel and the copper, the corrosion of copper is accelerated when the core is exposed.